Gaseous detector of radiant energy and method of control thereof



Dec-14,1926. 1,610,371

J. H. HAMMOND, JR

GASEOUS DETECTOR OF RADIANT ENERGY AND METHOD OF CONTROL THEREOF Original Filed Marh 21, 1914 .E E 3 b a k M: Q 3

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Patented Dec. 14, 1926.

UNITED STATES, PATENT OFFICE.

, JOHN HAYS HAMMOND, JR., OF GLOUCESTER, MASSACHUSETTS.

GASEOUS DETECTOR OF RADIANT ENERGY AND METHOD OF CONTROL THEREOF.

Application filed March 21, 1914, Serial No. 826,257. Renewed m 24, 1923.

' This invention relates to gaseous or vacuumized detectors of radiant energy and method of controlling the action thereof.

In order that the principle of the invention may readily be understodd, I shall describe certain embodiments of said detector and certain methods for controlling the ac- 'In gaseous or 'vacuumize"-detectors, and particularly those of the so-called audion type, the sensitiveness thereof depends upon a number of variable factors, among which may be enumerated the nature of the rarified gas, the degree of the vacuum, and the character, form, and relative position of the plate, grid and filament. In the construction and operation of such type of detector, it is necessary that a certain ideal relation be approximated in the effect that the strength of the local flux and filament currents have on the control of the electronic flow through the detector by the charging of the grid thereof 'by high frequency low frequency alternating or oscillator -.-currents.

In the drawings, Figs. 1 and 2 represent plotted curves and Figs. 3 and dare diagrammatic representations of certain embodiments 01311163118 for practicing my invention. 3

In Fig. '1 I have represented the form of curve that is obtained in a detector of the proper construction and wherein the said ideal relation is approximated. The abscissa here represents the filament voltage and the ordinate the change of current flow through the audion as measured by a galvanometers deflections. The said curve is characterized by the'sharp rise which takes place at a certain critical value of the filament voltage. The voltage of the flux current and the potential gradient between the filament and plate might also be plotted as the abscissa and the current-change defiec' tions as the ordinate, but it is considered unnecessary here to illustrate the same. In such case the curve if represented would show increasing deflections with increase of flux current potential (with increase of potential difference) between the filament and the -plate. However, in the last case the curve would not show the steepness existing in the case where the filament voltage is varied, but in order to obtain the maximum sensitiveness, it is necessary that the voltages of the flux and filament be changed with respect to each other. In Figure 2 l have-represented a curve in which the detector is insensitive and the detector acts more as a rectifier than a so-called trigger device.

In order that the detector shall be set.

to break down and the detector will be unable to recover its original sensitive condition and will possess only rectifying properties. -When the detector is adjusted'to a point where it is highly sensitive, slight variation of local conditions or a powerful signal may cause the gas to break down and the detector is therefore tion.

I have by my invention secured the desired results, and therefore am enabled thereby to obtain and to utilize the delicate setting of the detector, with reliability of operation thereof. The detector herein disclosed constitutes a gaseous amplifier of feeble electricity. Y In accordance with the preferred embodiment of my invention to which, however, I

out of operaamnot limited, I effect periodic changes of value or periodic amplitude variation of a local current, and preferably I effect a pe riodic drop of a local current to zero value in any manner. While such periodic drop may be effected in any suitable manner, I

preferably effect it by the employment of interrupting means. for one or both of said circuits. I shall describe certain means for effecting this result, but it is to be distinctly understood that. I am not limited thereto, and that withinits broad scope my invention may be otherwise carried out than by efiectmg a zero va ue.

Figure 3 I have represented one type of means for eifecting the desired results and for the practice of my invention and the method involved therein.

. Insaid Figure 3 the primary of an oscillatory transformer of an open receiving eriodic drop of a local current to aerialcircuit is represented at 1. The secthe cathode of the detector.

ondary winding of the closed oscillatory cir- (suit is represented at 2. A condenser is represented at 3 andthe vessel or bulb-like chamber of the detector is indicated at 4. Suitably mounted in the said chamber is a filament 5 heated in any suitable manner as by a battery 5. Thisfilament 5 constitutes The grid is indicated at 6, it being connected in any suitable manner to the closed oscillatory circuit, and the anode or plate is represented at 7. The chamber 4 contains a suitable rarified gas, such, for example, as mercury vapor. While it is possible to stop any brush effect by the use of a very high vacuum in the tube, nevertheless in this condition the detectors are not as sensitive. There is a critical degree of vacuum necessary for the higher sensitiveness of .the detector. The filament or cathode 5 and the plate or anode 7 are externally connected by the conductors 8, 9, the flux circuit having therein a local battery 10 in series with the detector and the telephone 11 or other indicating or recording instrument or device. In series also with the detector, local battery and indicating or recording device, is an interrup ter 12 which is here represented as shunted by a condenser 13, the said interrupter making suitable. contact at 14 thereby to interrupt the current through the detector. It

I is desirable when telephonic reception is used, that the frequency of the interrupter be somewhere about one thousand per second so that a high pitched sound may be produced in the telephone. The diaphragms of the telephones may also be made resonant to the frequency of the interrupter. The frequency of the interrupter may, however, he obviously suitably varied within the scope of my invention. The function of the condenser 13 is to cause a more definite and sudden break in the direct current source through the detector, this being achieved by the elimination of arcing across the points of contact.

While I have made reference to the detector as used with an indicating or recording instrument or device, it is evident that it may be used for other purposes, as, for example, in the control of devices or mechamsms, among which may be enumerated vessels or other moving bodies.

It is well understood in the art that the general type of gaseous detector herein referred to operates throu h the action of the negative charge accumu ating on the grid from the action of the oscillatory currents created in the closed circuit from those produced in the open aerial circuit by the action of electromagnetic Waves. This accumulation of a negative char e changes the slo e of the potential gra ient from the cat ode so that the electrons are interrupted in their flight to the positive plate or anode.

The rectifying effects of the cathode current cause the detector to act as a rectifier and there is produced the so-called valve action in which the negative side of the high frequency alternating or oscillating currents is caused to remain on the grid, thereby producing an ultra negative point with respect current takes place across the gas, there is an ionization set up which produces a flow of positive ions toward the cathode. These positive ions approaching the steep potential gradient in the immediate vicinity of the cathode, accelerate, and striking the cathode with great velocity cause a fresh discharge of electrons. In this way the action repeats itself indefinitely. However, if the local current be interrupted in any manner, as by a suitable form of interrupter of which one form is shown in Fig. 3, then the production of electrons ceases and the action stops, ionization of the gas stops, and the detector is restored to its original condition of high insulating resistance." The detector is byv my invention maintained in a condition of high insulating resistance and is by my invention maintained sensitive to receive signals. Thus the detector is selfrestoring, which constitutes an important feature of my invention. In this way the detector may be set safely at a oint of maximum" sensitiveness and will operate with reliability. I may, in any suitable mannerand within the scope of my invention, effect amplitude variation in the electrical currents in the controlled circuit at sufliciently short periods to maintain the detector properly sensitive to receive signals. I may, in any suitable manner and within the scope of my invention, cause the stoppage of the ionization of thegas consequent upon the electronic discharge, and thereby maintain the detector properly sensitive to receive signals. I

In Figure 4 I have represented a somewhat modified form of detector embodying my invention and by which I may practice my rocess. Therein the primary of the oscil atory transformerijis indicated at 15 and the secondary winding of the-closed oscillatory circuit is indicated at 16.- The chamber or bulb is indicated at 17, ithaving therein a suitable tantalum or other filament 18 constituting the cathode and heated by a a crably a suitable condenser 21 is employed in the closed oscillatory circuit. Within the bulb is a suitable grid 22 in communication with said closed oscillatory circuit, Also suitably mounted in the tube is the plate 23 constituting the anode. The filament or cathode and plate or anode are connected externally by the 'flux circuit 24 having therein a local battery 25 and a telephone 26 or other suitable indicating or recording instrument.

In accordance with my invention I cause a periodic drop of a local current to zero value and in the present embodiment of my invention wherein I have shown both a filament circuit and a flux circuit I preferably periodically and synchronously interrupt both the flux current and the filament cur- .rent. For this purpose I have herein repreby they are rotated in synchronism. Each of said disks is provided with suitable contacts 30, 31, with which periodically contact brushes 32, 33, of the filament and fiux circuits respectively.

The shaft 29 may be rotated in any suitable manner and at such speed as to effect the proper periodic drop of both local circuits to zero value.

In the manner described or in any other suitable manner I may cause a periodic dro of a local current to zero value, and accor ingly, by the practice of my'method, secure the results heretofore referred to.

Having thus described certain embodiments of my invention, and certain methods for practicing the same, I desire it to be understood that the terms herein employed are used in a generic sense and not for purposes of description, the scope of the invention being set forth in the following claims.

Claims.

1. A gaseous detector of radiant energy,

' having a heating circuit for said filament cathode, and means to interrupt said circuit at suflicientl short periods to maintain the detector e ectively sensitive to receive signals.

2. A gaseous detector of'radiant energy comprising a container of rarified gas having a filament cathode, an anode, and potential gradient changing means, said detector having a heating circuit for said filament cathode, and also a circuit including said cathode and anode, and means for synchronously interrupting both of said circuits.

3. A gaseous detector of radiant energy comprising a container ofrarified gas having a cathode and anode, and potential gradient changing means, said detector having a circuit including said cathode and anode, a

telephone in said flux circuit, an interrupter in said circuit in resonance with the frequency of the telephone diaphragm.

4. A gaseous detector of radiant energy- 5. A thermionic wave responslve device comprising a container provided with a' cathode, an anode, and potential gradient changing means, a circuit for heating said cathode, said circuit being providedwith means for interru ting the same at sufficiently short perio s to maintain the device efl'ectively sensitive to receive signals.

6. A thermionic wave responsive device comprising a container provided with a cathode, an anode, and potential gradient changin means, and a circuit for heating said cathode, said circuit including means operative to cause a drop of the current therein to a zero value at sufiiciently short periods to 'maintain the device effectively sensitive to receive signals.

7. A thermionic wave responsive dvice cathode, an anode, and potential gradient changing means, said device havin a circuit including said cathode, and sai anode, a telephone receiver, a periodic interrupter, said telephone receiver being provided with a diaphragm which is resonant to the frequency of the interrupter.

8. A wave responsive device, comprising a cathode, an anode, and potential gradient changing means, said dev1ce havin a heating circuit for said cathode and a so a circuit including said cathode, and said anode,

and means automatically operative to interrupt both of said circuits s chronously.

9. A gaseous detector o radiant energy having a cathode, an anode, and potential gradient changing means normally acting by decreasing the/ current of the controlled circuit, said detector havin a local circuit, and means to interrupt sai circuit at sufficiently short periods to maintain the detector eifectively sensitive to receive "signals;

10 A gaseous detector of radiant ener having a cathode, an anode, and potentlal gradient changing, means normally acting y decreasing the current of the controlle circuit and means to causea drop to zero value of the current in the controlled circuit at sufliciently short intervals to render said detector self-restoring.

11. A gaseous detector of radiant energy having a cathode, an anode, and potential gradient-changing means, normally acting by decreasing the current of the controlled circuit, a local current source controlled by the action of said detector, and of the circuit whereof the detector constitutes a part, and means automatically to cause a drop of said local current to zero value, at suiliciently short periods to maintain the detector in a condition of relatively low insulating resistance, thereby to effect sell"- restoration of said detector.

12. A gaseous detector of radiant energ having a cathode, an anode, and potential gradient-changing means normally acting by d creasing the current of the controlled circuit, said cathode and said anode being included in said controlled circuit, and means to interrupt said controlled circuit at suiiiciently short periods to maintain the detector effectively sensitive to receive signals.

13. A gaseous detector of radiant energy having a cathode, an anode, and potential gradient changing means, a circuit controlled by said detector, and including a.

a source of energy, said circuit normally having a current flowing therethrough, and said detector normally acting to decrease said current upon receiving a signal, and said circuit including an -automatic interrupter arranged to interrupt said circuit periodically and at sufficiently short periods to maintain the detector-effectively sensitive to receive signals.

cuit periodically and at sufliricntly short periods to maintain the detector effectively sens two to receive signals.

15. A gaseous detector of radiant energy having a cathode, an anode, and potential gradient changing means, a circuit controlled by said detector, and including asource of energy, said circuit normally having a current flowing therethrough, and said detector normally acting to decrease said current upon receiving a signal, and said circuit including an automatic vibratory interrupter arranged to interrupt said circuit periodu ally and at suiiiciently short periods to maintain the detector effectively sensitive to receive signals, and a condenser shunted around said interrupter for the elimination of arcing across the points of contact of the interrupter.

In testimony whereof, name to this specification.

J OHN HAYS HAMMOND, J 1:.

I have signed my 

